In this research we developed an online trading card game (something like Yu-Gi-Oh!)
and used the trading cards as educational rewards to enhance students' motivation in
using an online English lecturing and assessment system.
Peayton Chen, Rita Kuo, Maiga Chang, and Jia-Sheng Heh. (2009). Designing a Trading Card Game as Educational Reward System to Improve Students' Learning Motivations. Transactions on Edutainment,
III, 116-128. Berlin: Springer-Verlag.